The present invention relates to a polishing composition used in the polishing process for example for forming wirings for semiconductor devices.
High-density, high-speed ULSIs are manufactured in accordance with fine design rules. In order to inhibit the elevation of wiring resistance due to the refinement wirings on semiconductor devices, copper is used as a wiring material.
Since metallic materials containing copper have characteristics that processing by anisotropic etching is difficult, a wiring formed from a metallic material containing copper is formed using the following chemical mechanical polishing (CMP) method.
First, a wiring trench is formed in an insulating film. A barrier film of tantalum or a tantalum compound such as tantalum nitride is formed on the insulating film. A conductive layer of a metallic material containing copper is formed on the barrier film so that at least the wiring trench is completely buried. The conductive film is polished until the upper surface of the barrier film is exposed (first polishing). Next, the barrier film is polished until the upper surface of the insulating film is exposed (second polishing). Thereby, a wiring is formed in the wiring trench.
Japanese Patent Laid-Open No. 2000-160139 discloses a first prior art polishing composition containing a polishing ingredient such as silicon oxide, an oxidizing ingredient such as hydrogen peroxide, a reductant such as oxalic acid, and water. Japanese Patent Laid-Open No. 2001-89747 discloses a second prior art polishing composition containing a polishing ingredient such as silicon oxide, oxalic acid, ethylenediamine or the derivative thereof, benzotriazole or the derivative thereof, and water. The polishing ingredient has the function to mechanically polish a surface. The oxidizing agent, the reductant, and oxalic acid have the function to accelerate the polishing of a barrier film.
However, when the polishing compositions of the first and second prior art are used in the above-described second polishing process, the level of the upper surface of the insulating layer in the wiring region becomes lower than the level of the upper surface of the insulating layer in the region other than the wiring region, and local erosion occurs (refer to FIG. 3).
The object of the present invention is to provide a composition for polishing semiconductor devices that does not easily cause erosion.
To achieve the above object, one aspect of the present invention is a polishing composition, used in a manufacturing process of a device that includes an insulating layer having a wiring trench formed therein, a barrier film formed on said insulating layer, and a conductive layer formed on said barrier film to bury said wiring trench. The polishing composition can be used for polishing said barrier film to expose an upper surface of said insulating layer, and includes silicon oxide and a polyoxyethylene alkyl ether sulfate represented by formula 1.
R1xe2x80x94Oxe2x80x94(C2H4O)nSO3xe2x80x94Xxe2x80x83xe2x80x83(1)
wherein R1 is an alkyl group having 3 to 20 carbon atoms, n is an integer from 2 to 30, and X is sodium, potassium, ammonium, or triethanolamine. The composition further includes a benzotriazole corrosion inhibitor; at least one acid selected from a group consisting of nitric acid, hydrochloric acid, sulfuric acid, lactic acid, acetic acid, oxalic acid, citric acid, malic acid, succinic acid, butyric acid, and malonic acid; and water.
Another aspect of the present invention is a method for manufacturing a polishing composition, used in a manufacturing process of a device that includes an insulating layer having a wiring trench formed therein, a barrier film formed on said insulating layer, and a conductive layer formed on said barrier film so as to bury said wiring trench, said method comprising a step of mixing silicon oxide; a polyoxyethylene alkyl ether sulfate represented by formula 1,
R1xe2x80x94Oxe2x80x94(C2H4O)nSO3xe2x80x94Xxe2x80x83xe2x80x83(1)
where, R1 is an alkyl group having 3 to 20 carbon atoms, n is an integer from 2 to 30, and X is sodium, potassium, ammonium, or triethanolamine, a benzotriazole corrosion inhibitor; at least one acid selected from a group consisting of nitric acid, hydrochloric acid, sulfuric acid, lactic acid, acetic acid, oxalic acid, citric acid, malic acid, succinic acid, butyric acid, and malonic acid; and water.
Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.